Time-limit elevator control



-J. W. DODD Filed Sejnz. 5. 1921 C'uvreaune Patented May 6, 1924.

UNITED STATES PATENT. OFFICE.

JOHN -W. nom), OF QUINCY, MASSACHUSETTS, ASSIGNOE TO GEORGE T. MCLAUTHLIN COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION or RHODE ISLAND.

TIME-.LIMIT ELEVATOR CONTROL.

Applicatonled September 3, 1921. Serial No. 498,366.

To all whom t lmay ooncem p Be it known that I, JOHN lV. DODD, a citizen of the United States, residing at Quincy, in the county of Norfolk and State of lilassachusetts, have invented new and useful Im roveinents in Time-Limit Elevator Contro s, of which the following is a specilication.

This invention relates to means for actuating and controlling elevators, being more particularly designed to provide for automatically stopping the actuation of the propelling power should the elevator Car for any reason be obstructed in its movement. In elevator systems of the traction type in which hoisting cables are passed about anarc of a traction sheave instead of being wound on spools or drums, an obstruction tothe descent ofthe car or counterweight causes slippage between the traction sheave and cable, causing wear on the able and cutting of the sheave. Even though this slipping occurs neither side of the cable may be slackened sufficiently to actuate an automatic power cut-out so that devices dependent on the slackening of the cable for actuation are unreliable for this type of'drive.

This invention provides a construction for effecting the stoppingr of the power which is not dependent onvslackening of the cables so that it may be used on elevators of the traction type. For this purpose a time controlled element is incorporated in the elevator control being set for a time somewhat in excess of the entire time necessary7 for a complete traverse of the elevator car in one direction. If then the power is on continuously for a period longer than this at. one time, it is evident that the car travel has been obstructed somewhere on the way. The time controlled element then automatically acts to shut off the power.

For a more complete understanding of the invention together with further objects and advantageous details and combinations of parts, reference may be had to the accompanying Ydrawings in which- 1 Figure l is a wiring diagram of a three phase electric elevator control employing a time element stopping switch.

Figure 2 is a diagrammatic view of an elevator and actuating mechanism of the traction type.

Figure 3 is a partial diagram of a direct current elevator power system employing this invention.

Referring to Figure 2, at l is shown an elevator having an actuating cable at 2 passing over a sheave 3 at 'the upper end of the path of traverse, a counterweight 4 being provided to partially balance the elevator and its load. The cables 2 are passed about an arc of the sheave 3, which is driven by means of an electric motor, or other source of power shown at Ala.

Referring now to Figure 1, the motor., in this case a three phase electric motor, though it might be any director alternating current motor, is shown at 4e, a` reversing and controlling switch therefor being shown at 5, this controller being carried by the car and actuated by the operator in the usual manner. At 6 is shown a magnet-ic main switch interposed between the controller 5 and the motor. This switch comprises an actuating or closing magnet 7 which, when energized, closes the main 'switch contacts at 8 to complete the motor circuit. The magnet 7 is interposed in a shunt circuit across the main switch terminals 8 on the power side, this shunt cir cuit having a switch 9 interposed therein which may be actuated by a time element relay shown at 10 sothat after a predetermined time in which current is flowing in the shunt circuit, the switch 9 will be opened to oen this circuit. Then this action takes p ace the main switch is allowed to open due to the de-energization ofL the magnet 7.

The time element relay 10 is of any usual type, such switches being Old and well known in the art, and hence no detailed description is necessary. The relay is shunted across the motor lines as shown at ll-ll so that whenever the motor is running the time relay will be energized. Vhile Fig. 1 shows a relay connected across one phase an additional relay may be connected across another phase and actuating switch 9 or a similar switch in the same circuit. Thile the switch 6 is shown as of the norinally open type it will be evident to those skilled in the art that an equivalent construction might be employed in which the time. relay might actuate a tripping coil circuit to open the main switch 9 instead of the construction shown. As such a mechanism is well understood in the art no showing thereof is deemed necessary in this case. The time relay element is adjusted to break the switch 9 after a period of actuation of the motor la sufficient to normally cause theelevator to make a complete traverse in one direction. For example, it the entire time of travel-sect the elevator is one minute, the relay will be set for somewhat over one minute.l Whenever the controller is moved to the off position, as when it is desired to stop the elevator either at the ends of its traverse, or at any intermediate point, the relay goes back to starting position in the usual manner, but as soon as the controller is moved to start the elevator the time actuation of the relay commences.

In Figure 3 the connections ot 'relay and control circuit tor a direct current installation are shown. In this system the no1-mall open main switch is shown at 8, this switc i as shown being ol' they single ypole type, but a double pole switch might be substituted if desired. At 7 is shown the solenoid for closing and holding closed the switch 8. A time element relay at l0 is utilized to break the control circuit to cle-energize the solenoid 7 by means ot a switch 9, the opening of this switch breaking the circuit through both the switch closing coil 7 and the relay 10, the switch 8 being allowed to open as soon as the coil 7 is cle-energized.

It is preferable to'employ a switch tor actuation by the time element relay, as 9 and 9 on the drawings, of a type which' must be closed by hand, since should the relay operate to open this switch, inspection of the installation to determine reason tor the delay ot the elevator and to eliminate this reason should be made before 'further running is permitted.

From the above description it is evident that this invention provides a mechanism which may be utilized on all traction type electric elevators and which will insure the stopping of the actuating power within a reasonable time after the elevator car or counterweight meets an obstruction in its path and ceasesto move. As this mechanism is entirely independent of any slackening of the cable, lack of motion of the car of weight, or other effect on, or condition or the operating mechanism or car produced by the obstruction, but is a time control only, it is effective for various types of motive power and driving systems.

lVhile this invention has been described in connection with electric propulsion, it is evident that the ideais also applicable to other types of motive `power in a manner which will be obvious to those skilled in the art.

Having thus described this invention', what I claim to be new is:

1. A device of the class described comling a traversing car, an electric motorfor moving said car, a controller for said car, and a time controlled element for cutting oit the power independent of said controller after a time normally sufficient to effect a complete traverse of said car in one direction.

3. A'V'control system for an electrically i operated elevator comprising an electric motor for moving the elevator car, a switch for controlling said motor, a controller for actuating said switch, and a time element relay for causing said switch to break the motor circuit independent of said controller after said switch has been closed for a predetermined time.

4. A control system for an electrically operated elevator comprising an electric motor for moving the elevator car, a motor circuit, a normally open switch in said circuit, a motor reversing controller for said circuit, and a time element relay shunted about said switch and actuable to open said switch after a predetermined time after said circuit is closed by said controller, unless the circuit is sooner opened by said controller or other means.

l 5. A control system for electrically operated elevators comprising a reversing motor for actuating the elevator car, a controller for said motor, a normally open main switch interposed between said controller and motor, a circuit in shunt with said motor and main switch, means actuable on the clos-ing of said shunt circuit tor closing and holding closed said main switch, a switch in said f shunt circuit, and a time element relay in said shunt circuit tor opening said shunt switch to permit said main switch to open at a predetermined time after the actuation of said controller to start the motor.

6. A device of the class described comprising a traversing car, power means for moving said car, and a time control element for cutting oil the power after a predetermined time irrespective ot the condition of said means.

7. A'device of the class described comprising a traversing car, an electric motor for moving said car, a controller for said car` and a time controlled element for cutting o the power independent of said controller and the condition of said car atter a predetermined time.

In testimony whereof I have aiXed my signature.

JOI-IN W. DODD. 

